SOD1 and diabetes mellitus: Furthermore, the observed increase in erythrocyte Cu,Zn-SOD, associated to a decrease in GPx, leading to a higher risk of H2O2 accumulation, is a common feature of the route toward type 2 diabetes mellitus [26], ageing [27], and neurodegenerative diseases like a Down syndrome due to a overexpression of SOD without increased in GPx [28].